Case Study: Ground Water Infiltration For Sellafield

Managing suspended solids and silt during groundwater abstraction or site dewatering is a critical compliance challenge across industrial and nuclear environments. Discharge limits require precise filtration before water can safely enter drainage networks, while inefficient systems often lead to heavy landfill disposal costs for saturated sludge.

To address this, Cowens designed and manufactured a custom, high-efficiency groundwater filtration unit for site operations at Sellafield. The engineered solution enables continuous silt removal, ensuring water meets stringent discharge consents while significantly reducing waste handling overheads.

The Engineering Challenge: Silt Removal & Regulatory Compliance

Groundwater at industrial sites frequently contains high concentrations of fine silts, particulate matter, and suspended solids. Returning untreated water to drainage risks non-compliance with environmental regulatory standards and sewer discharge consents.

The primary objectives for the Sellafield deployment were clear:

• Sub-10 Micron Clarity: Achieve ultra-fine particle filtration to ensure water is clean enough to return directly to the site drain.
• Safe & Easy Maintenance: Eliminate heavy manual handling risks when removing and emptying accumulated solids.
• Cost Optimization: Minimize landfill disposal expenses associated with wet silt waste and reduce overall operational expenditure.

The Solution: Multi-Stage Filtration & Custom Geotextiles

Cowens designed a robust, two-phase filtration system engineered specifically for high-solids throughput and ease of maintenance.

Key technical components of the unit include:

• Custom High-Strength Siltscreen Bag Filter: Utilizing our proprietary heavy-duty geotextile (Siltscreen), Cowens stitched a purpose-made bag filter designed to handle heavy sediment loads without tearing.
• Customized Steel Primary Tank: The Siltscreen filter is housed inside a custom-built steel tank, serving as the heavy-duty coarse filtration stage.
• Ergonomic Top-Lid Suspension: A unique lid-mounted hanging mechanism supports the filter bag. This innovative design completely avoids manual handling strain during maintenance and makes emptying captured solids fast and straightforward.
• Polished Two-Stage Secondary Filtration: The primary tank outlet pumps water through a specialized two-stage vessel system, stripping remaining particulates down to sub-10 micron size.

The Outcome: Low Maintenance, High Efficiency & Full Compliance

By prioritizing visual monitoring and mechanical simplicity, the filtration system delivers exceptional reliability without complex operational demands.

Key Success Metrics:

• Discharge Consent Assured: Water is consistently reduced to sub-10 micron particle clarity, fully satisfying discharge requirements.
• Reduced Waste Costs: Efficient silt isolation minimizes wet landfill volume, drastically lowering disposal fees.
• Process Flexibility: The clean water output can be returned to drainage, reused in process streams, or recycled across site operations.
• Visual Control: Complete visibility across all filtration stages allows site operatives to inspect flow quality and monitor filter capacity at a glance.